Document the agent env vars; make keeping docs true a standing rule

README's config table gained OLLAMA_CLOUD_API_KEY and PANSY_AGENT_MODEL, marked
as read once the assistant lands (#56) so the table describes what the binary
does rather than what it will do. Both are already set in Komodo.

Also fixed the Compose example, which still said "# PANSY_OIDC_ISSUER: ... once
auth (#5) lands" — auth landed a long time ago. That is exactly the kind of rot
this commit is trying to prevent, so it seemed worth fixing in the same breath:
the snippet now shows the OIDC vars people actually need to set.

CLAUDE.md now carries the rule explicitly. README updates go in the SAME commit
as the change that needs them — the env var table and the compose snippet are
the two things people copy, so they hurt most when stale. DESIGN.md tracks real
architecture changes. Examples must run. And when you touch a file, check the
comments around your change are still true, because a stale comment is worse
than none: the next reader believes it.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01H3zbym8Doka2d7D48maSgZ

CLAUDE.md

@@ -21,6 +21,28 @@ Rules, not preferences:
 If you find yourself editing that section, the only acceptable direction is
 clearer and more honest, never quieter.
 
+## Keep the docs true
+
+Docs rot silently and nobody notices until someone follows them and it doesn't
+work. Treat them as part of the change, not follow-up work:
+
+- **README.md** — update it in the *same commit* whenever you add or change an
+  environment variable, a route worth knowing about, a build or run command, or
+  anything in the Docker/Compose example. The env var table and the compose
+  snippet are the two things people copy, so they're the two that hurt most when
+  they're stale.
+- **DESIGN.md** — update it when the architecture actually changes: a new table,
+  a new package, a new API surface, a decision that supersedes one written there.
+  Not for every implementation detail.
+- **CLAUDE.md** — this file. Add a convention here the moment you find yourself
+  rediscovering it.
+- **Examples must run.** If you change something an example depends on, fix the
+  example. A snippet that references an issue number as "once #5 lands" after #5
+  has landed is a bug in the docs.
+
+When you touch a file, glance at whether the comments around your change are
+still true. Stale comments are worse than none — the next reader believes them.
+
 ## Build and test
 
 pansy is a standalone Go module inside a parent workspace, so **`GOWORK=off` is